Stander, H-M, Du, S, Mokomela, R & Broadhurst, JL 2025, 'An integrated approach for waste repurposing and environmental remediation 
in the South African coal mining industry', in S Knutsson, AB Fourie & M Tibbett (eds), Mine Closure 2025: Proceedings of the 18th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-15, https://doi.org/10.36487/ACG_repo/2515_54
(https://papers.acg.uwa.edu.au/p/2515_54_Stander/)
Abstract: Coal is an important energy source for the South African economy and is likely to remain so in the medium term, but several mines are nearing closure. Coal extraction, processing and combustion, however, produce industrial wastes, which can be toxic to the surrounding natural and agricultural environments, as well as the health of nearby communities. Discards and tailings from washing operations occupy large tracts of land, sterilising these for a variety of uses and require post-mining landform shaping. These also represent a longterm acid rock drainage risk. Coal combustion waste, especially fly ash, also occupy large tracts of land and is a potential source of water pollution due to high metal loads and high pH’s. Current waste management approaches, including co-disposal, lining tailings dams and covering waste facilities with soil and vegetation, require monitoring and maintenance over a long timeframe and carry a risk of environmental failure.
To reduce the need for post-closure waste management and increase the number of post-closure land use options, an integrated circular-economy approach aimed at valorising whole waste bodies and simultaneously remediating the surrounding environment has been proposed. This approach makes use of and remediates the solid waste, fly ash, acid mine drainage, and mining affected soils. In this paper, the industrial ecology approach is specified, the relative volumes of each waste stream are estimated, and the materials streams are calculated. It is estimated that – in addition to avoiding waste disposal – this approach could annually return 135,000 Mℓpa of irrigation-quality water to Mpumalanga province, rehabilitate 12.6 km2 of mining impacted land with fabricated soil, ameliorate 20,000–63,000 ha of alkaline or sodic soils, and produce 40 Mm3 of backfill material on a regional scale. This approach can also produce nano-iron and sulphuric acid.

Keywords: regionally integrated waste repurposing, coal mine waste, acid mine drainage, fly ash, mining affected soils